How many solutions does the system have?
x+y=3
5x+5x= 15
a) exactly one solution
b) no solutions
c) infinitely many solutions

y = 3/2 , x = 3/2

Step-by-step explanation:

Solve the following system:

{x + y = 3 | (equation 1)

10 x = 15 | (equation 2)

Divide equation 2 by 5:

{y + x = 3 | (equation 1)

0 y+2 x = 3 | (equation 2)

Divide equation 2 by 2:

{y + x = 3 | (equation 1)

0 y+x = 3/2 | (equation 2)

Subtract equation 2 from equation 1:

{y+0 x = 3/2 | (equation 1)

0 y+x = 3/2 | (equation 2)

Collect results:

{y = 3/2 , x = 3/2

cbnygjdyj

step-by-step explanation:

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional